Triple Bipolar VCA

Intoducing the WMD Triple Bipolar VCA, the input side expansion for the Phase Displacement Oscillator. This module provides dedicated inverting/polarizing/bipolar amplitude modulating inputs normaled to the Phase Modulation inputs on the PDO.

A bipolar VCA is like a normal VCA when operated with positive control voltage. But when using a negative control voltage, the output will swing back through zero amplitude and the output will be inverted. This produces deeper modulation than a normal VCA.

The Triple Bipolar VCA is also designed to be used as a standalone module, it does not require the PDO to operate.

Three Bipolar VCAs

Normaling to PDO

Linear Response

Bipolar Attenuator for CV

Mix Output Sums All Three VCAs

Bi-color Signal LEDs

"-" Input for Mix Through Zero

Skiffable PCB Design

8 HP

+80mA/-75mA Current Consumption

Controls and I/O

+ IN - This is the normal input for each VCA channel. It drives the inverting side of the Bipolar VCA. These inputs are normaled from outputs on the PDO.

- IN - This is the second input for the VCA channel. Normaled through this jack is the inverted signal from the + Input. Plugging in here converts the channel from a Bipolar VCA to a dual VCA. Negative control voltages will open the - side, and positive control voltages will open the + side. This allows you to use two modulation sources and alternate between them, while still retaining control over amplitude.

CV - This input jack drives the CV knob. It can handle unipolar or bipolar signals.

OUT - This is the output of each VCA channel. They are normaled to the Phase Modulation inputs on the PDO.

BIAS KNOB - Sets the manual gain for the VCA. Centered will have a zero output (with 0V control voltage).

CV KNOB - This knob is a bipolar attenuator for the signal applied to the CV jack. Spin clockwise from center for positive CV interactions, counterclockwise to invert the CV.